I pretty much BB and kite, on the 2nd and 3rd fight I use implosion when its up. As for the last fight I drop a BB at the floating runes leading into the room and 1 at the altar and just do circles around letting him get hit twice per BB he passes through. I use enevate/destruction on the humanoid looking ones if they are just standing there casting at me and not moving through BB.
Takes me about 10ish mins on normal, only did it on elite solo once and took me around 20, but it was also my first attempt and I didnt know what to expect, I could prob do it in 15 now.
I actually had eardweller drop twice for me. I thought it was supposed to be a drop in the clam and saw it run off but ignored it the first time and left. The second time my fire ele attacked and killed it.
You cannot ransack the clam, but you can ransack the completion reward.